By Hugh McFall
It’s increasingly common to hear the steady hum of a drone flying on a construction site. They’re being used to share progress updates from the sky, manage earthworks, perform cut-and-fills, and much more. But, there’s also an emerging use case for drones within the civil engineering space: As designers move from 2D toward 3D design and BIM workflows, the reality capture data that drones provide is making a huge impact on their projects. In short, drones are the latest tool in the civil engineer’s workflow, and they’re changing the way the world gets built.
To show how, 3D Robotics (3DR) recently embarked on a project with Autodesk — working with their team of bridge design and reality capture specialists — to explore the impact that drones are having on infrastructure projects.
We set out to show the complete drone-to-design workflow on a real-life project and quickly identified a great example — the Pinto Creek Bridge, an aging structure east of Phoenix that the Arizona Department of Transportation is demolishing and replacing. Drone data is particularly useful for a site such as Pinto Creek because it’s a large, steep ravine that a drone can quickly survey. Going out in the field to collect this data would be time consuming and, at times, unsafe. Also, flying a drone doesn’t require closing the road for manual inspection, which is particularly useful because there are no easy detours around the bridge.
3DR’s Site Scan drone-to-data platform captured the entire area in a single flight. The flight took 30 minutes, collecting 358 high-resolution photos. Then, after processing the images into a number of different data products, we delivered a detailed point cloud to the Autodesk team for processing.
Ramesh Sridharan, product manager at Autodesk, imported the raw point cloud data into InfraWorks and processed it to extract and classify the features of the terrain. As the only structure in the area, it was easy to classify the bridge (shown in purple in Figure 1), and remove it. In a matter of hours, the point cloud was filtered and a complete model was set up — aggregating point clouds, elevation data, and existing infrastructure — that provided a rich context in which to design the bridge.
According to Sridharan, using a point cloud provided by drone data “improves the speed, efficiency, and convenience of designing and modeling existing conditions. Fine details help designers identify existing problems, and then they can propose sound solutions for infrastructure challenges.”
Designing the new bridge
Once the point cloud was prepared for design, Ara Ashikian, senior product line manager at Autodesk, created a number of bridge models with InfraWorks in a matter of hours. He customized road alignments and grading, and could easily modify the parameters of each component that made up the bridge. The magic is behind the scenes: Each component is fully parametric and dynamic, so designers can make changes while maintaining engineering principles.
“Drone data can create rich point clouds, which are incredibly useful to guide parametric bridge modelling,” Ashikian said. “With the Pinto Creek point cloud, I designed a bridge within the real-world context of the surrounding ravine and its features.”
In just two clicks, Ashikian sent the final bridge into Autodesk Revit to perform more detailed design. Because all of the underlying components of the structure were based on parametric geometry, they could easily be exported into Revit and other tools without needing to recreate them or perform any re-work.
Too often, civil engineers work with outdated surfaces when starting the design process. It can be difficult to access a reliable point cloud, so they fall back on old survey data, satellite images, or blueprints as a replacement. Drones are fixing that. Now, designers can quickly and easily collect up-to-date data on existing site conditions and design with confidence.
By putting drone data into tools such as InfraWorks, civil engineers are able to rapidly design in 3D, then share models with clients and other stakeholders far earlier in the project. This makes it easier to modify and iterate on the design before committing to a single one.
Our customers across the country — for example, Atkins, a multinational engineering and design firm — are integrating drone data into their preliminary design workflow. According to Chris Harman, civil engineer at Atkins, “If you can quickly and easily get a 3D version in front of a client, it avoids a lot of changes later on.”
Drones provide value long after the initial design phases, too. They enable constructors to digitize their jobsite as it evolves and compare as-builts to the original BIM or CAD models. This makes it easy to identify any issues before the fix becomes costly or time consuming.
Whether they’re looking to get feedback earlier in the infrastructure design process, create more accurate 3D concepts, or re-digitize the jobsite during the construction phases, drones and tools such as InfraWorks are proving to be crucial for engineering firms across the country.
Hugh McFall is a marketing specialist with 3D Robotics (www.3dr.com).